The present invention relates generally to the field of esophageal prosthetics. More specifically, a prosthesis delivery device is disclosed for submucosal insertion of a prosthetic bulking device.
Gastroesophageal reflux is a physical condition in which stomach acids reflux, or flow back from the stomach into the esophagus. Frequent reflux episodes (two or more times per week), may result in a more severe problem known as gastroesophageal reflux disease (GERD). Gastroesophageal reflux disease is the most common form of dyspepsia, being present in approximately 40% of adults in the United States on an intermittent basis and some 10% on a daily basis.
Dyspepsia, or heartburn, is defined as a burning sensation or discomfort behind the breastbone or sternum and is the most common symptom of GERD. Other symptoms of GERD include dysphasia, odynophagia, hemorrhage, water brash, and pulmonary manifestations such as asthma, coughing or intermittent wheezing due to acid aspiration. Dyspepsia may also mimic the symptoms of a myocardial infarction or severe angina pectoris. Many factors are believed to contribute to the onset of GERD including transient lower esophageal sphincter relaxations, decreased LES resting tone, delayed stomach emptying, and an ineffective esophageal clearance. Many in the field agree, however, that the primary cause of GERD is the lack of competency of the lower esophageal sphincter.
The lower esophageal sphincter, or valve, is comprised of smooth muscle located at the gastroesophageal (GE) junction and functions to allow food and liquid to pass into the stomach but prevent regurgitation of stomach contents. At rest, the LES maintains a high-pressure zone between 10 and 30 mm Hg above intragastric pressure. Upon deglutition, the LES relaxes before the esophagus contracts, allowing food to pass through into the stomach. After food passes into the stomach, the LES contracts to prevent the stomach contents and acids from regurgitating into the esophagus. The mechanism of LES opening and closing is influenced by innervation via the vagus nerve and hormonal control of gastrin and possibly other gastrointestinal hormones.
The severity of GERD varies from patient to patient and in extreme cases complications including esophageal erosion, esophageal ulcers, and esophageal stricture are observed. Esophageal stricture is a serious condition which results from prolonged exposure of the esophageal mucosa to acid reflux. The most common clinical manifestation of stricture is dysphasia. Unlike dysphasia from non-strictured esophageal reflux, dysphasia caused by stricture is progressive in that the size of a bolus which can pass into the stomach progressively becomes smaller. In addition to esophageal erosion and ulceration, prolonged exposure of the esophageal mucosa to stomach acid can lead to a condition known as Barrett""s Esophagus. Barrett""s Esophagus is an esophageal disorder that is characterized by the replacement of normal squamous epithelium with abnormal columner epithelium. This change in tissue structure is clinically important not only as an indication of severe reflux, but the appearance of columner epithelium in the esophagus is indicative of cancer.
Current methods to treat gastroesophageal reflux disease consist of lifestyle changes such as weight loss, avoidance of certain foods that exacerbate the symptoms of GERD and avoidance of excessive bending. Elevation of the head of the bed helps prevent nocturnal reflux. While these avoidance strategies may be helpful, there is relatively little data supporting the efficacy of lifestyle modification alone for the treatment of GERD.
Medications for the treatment of GERD have been administered for years with little or no success. Conventional antacids, such as TUMS(copyright) and ROLAIDS(copyright), produce short-term relief, but often have side effects including diarrhea and constipation. H2 receptor antagonists, such as Cimetidine and Ranitidine, are relatively more effective in controlling GERD symptoms but these symptomatic therapies fail to treat the underlying cause of the disease. More powerful secretory inhibitors, such as the proton pump inhibitors Omeprazole and Lansoprazole are more effective than the H2 antagonists but these drugs are expensive and, in the long term, produce negative side effects.
Surgery has become an attractive alternative for the treatment of GERD when lifestyle modification and medications fail to treat this debilitating condition. There are numerous reflux operations available which perhaps reflect the inadequacy of any one procedure to totally control the problem. The most commonly performed operation, Nissen Fundoplication, has been effective, but is often complicated by stricture formation or gas bloat syndrome. A laparoscopic Nissen procedure has also been developed, adding another dimension of difficulty, and long-term results remain questionable. In addition, a percutaneous laparoscopic technique has been developed. (See, for example, U.S. Pat. No. 5,006,106 to Angelchik). Minimally invasive techniques, such as transesophageal implantation of a prosthetic valve have also been attempted. (See, for example, U.S. Pat. No. 4,846,836 to Reich). Despite extensive attempts in the field to treat and prevent GERD, existing forms of treatment all have shortcomings.
In view of the foregoing, and notwithstanding the various efforts exemplified in the prior art, there remains a need for a minimally invasive bulking prosthesis and deployment methodology for transesophageal delivery into the vicinity of the lower esophageal sphincter.
In accordance with one aspect of the present invention, there is provided an overtube for coupling to the distal end of an endoscope to produce a submucosal prosthesis delivery device. The overtube comprises an elongate flexible tubular body, having a proximal end, a distal end and a longitudinal axis. At least one lumen extends into the tubular body, for receiving an endoscope. An opening is provided on the body, in communication with the lumen, and a limit surface is provided within the body, aligned with the opening to limit the depth to which tissue can enter the opening. Typically, the tubular body is defined by a sidewall and the opening is in the sidewall. The limit surface in one embodiment lies on a first plane which is offset from the sidewall and preferably is substantially parallel to the longitudinal axis. The limit surface is preferably provided with a plurality of apertures, to permit vacuum from the endoscope to draw tissue through the opening in the direction of the limit surface.
In accordance with another aspect of the present invention, there is provided a method of introducing a flowable media into a predetermined shape beneath a tissue layer. The method comprises the steps of identifying a first site on a tissue surface, and lifting tissue a predetermined distance away from the plane of the surface to create a low pressure zone beneath the tissue. A first volume of flowable media is injected into the low pressure zone so that the media takes on a shape which is influenced by the low pressure zone. The media is thereafter permitted to harden sufficiently to substantially retain the shape.
In one embodiment, the identifying a site on a tissue surface step comprises identifying a site on the wall of the esophagus. The site is preferably in the vicinity of the lower esophageal sphincter. The method may further comprise the steps of identifying a second site and introducing a second volume of flowable media into the second site, thereafter permitting the second volume of media to harden sufficiently to substantially retain the shape. At least one of the first and second site are preferably on the posterior wall of the esophagus.
In accordance with a further aspect of the present invention, there is provided a method of stabilizing a tissue site and introducing a prosthesis beneath the tissue. The method comprises the steps of providing an elongate flexible tubular device, having a side opening near a distal end thereof. The side opening is positioned at the site, and suction is applied to the device to draw tissue laterally into the side opening. Lateral advance of the tissue is limited by contacting the tissue with a limiting surface within the device. A prosthesis is thereafter introduced beneath the surface at the site while the tissue is in contact with the limiting surface.
In accordance with a further aspect of the present invention, there is provided a method of introducing a prosthesis beneath a tissue surface. The method comprises the steps of providing a prosthesis delivery device having an elongate body with a proximal end and a distal end, a concavity near the distal end, and an inner introduction lumen having a distal opening directed across the concavity. The concavity is positioned adjacent a site on a tissue surface, and tissue is drawn into the cavity. The prosthesis is advanced out of the distal end of the inner introduction lumen and through the tissue surface.
In accordance with a further aspect of the present invention, there is provided a delivery device for introducing a prosthesis beneath a tissue surface. The delivery device comprises an elongate body, having a proximal end and a distal end. A tissue stabilizing surface is provided on the body, and a prosthesis deployment lumen extends through the body, the deployment lumen having a longitudinal axis and a distal end. The distal end of the deployment lumen is positioned proximally of the tissue stabilizing surface. Preferably, the tissue stabilizing surface comprises a concave surface. The delivery device preferably comprises a lumen extending through the body and communicating with the tissue stabilizing surface, so that suction may be applied to the lumen to draw tissue adjacent the tissue stabilizing surface.
In accordance with another aspect of the present invention, there is provided a delivery system for delivering an expandable submucosal bulking agent. The delivery system comprises an elongate flexible body, having a proximal end, a distal end, and a tissue stabilizer near the distal end. A tubular cannula, having a sharpened distal end, is positioned within the body. The cannula is axially movable such that the sharpened distal end can penetrate tissue stabilized by the stabilizer. A plunger is movably positioned within the cannula, for ejecting bulking agent prepositioned within the cannula. In one embodiment, the plunger is distally advanceable beyond the distal end of the sharpened tip. Preferably, the tissue stabilizer comprises a cavity on a side of the flexible body. The tubular body comprises a lumen in communication with the cavity for applying vacuum to the cavity to draw tissue therein.
Further features and advantages of the present invention will become apparent to those of skill in the art in view of the detailed description of preferred embodiments which follows, when considered together with the attached drawings and claims.